Commit 06a4d0d8 authored by Yu Kuai's avatar Yu Kuai Committed by Song Liu
Browse files

md/raid5-cache: use READ_ONCE/WRITE_ONCE for 'conf->log' 



'conf->log' is set with 'reconfig_mutex' grabbed, however, readers are
not procted, hence protect it with READ_ONCE/WRITE_ONCE to prevent
reading abnormal values.

Signed-off-by: default avatarYu Kuai <yukuai3@huawei.com>
Signed-off-by: default avatarSong Liu <song@kernel.org>
Link: https://lore.kernel.org/r/20231010151958.145896-3-yukuai1@huaweicloud.com
parent 617787f1

drivers/md/raid5-cache.c

+25 −22
Original line number Diff line number Diff line
@@ -327,8 +327,9 @@ void r5l_wake_reclaim(struct r5l_log *log, sector_t space); 
void r5c_check_stripe_cache_usage(struct r5conf *conf)

{

	int total_cached;

	struct r5l_log *log = READ_ONCE(conf->log);



	if (!r5c_is_writeback(conf->log))

	if (!r5c_is_writeback(log))

		return;



	total_cached = atomic_read(&conf->r5c_cached_partial_stripes) +
@@ -344,7 +345,7 @@ void r5c_check_stripe_cache_usage(struct r5conf *conf) 
	 */

	if (total_cached > conf->min_nr_stripes * 1 / 2 ||

	    atomic_read(&conf->empty_inactive_list_nr) > 0)

		r5l_wake_reclaim(conf->log, 0);

		r5l_wake_reclaim(log, 0);

}



/*
@@ -353,7 +354,9 @@ void r5c_check_stripe_cache_usage(struct r5conf *conf) 
 */

void r5c_check_cached_full_stripe(struct r5conf *conf)

{

	if (!r5c_is_writeback(conf->log))

	struct r5l_log *log = READ_ONCE(conf->log);



	if (!r5c_is_writeback(log))

		return;



	/*
@@ -363,7 +366,7 @@ void r5c_check_cached_full_stripe(struct r5conf *conf) 
	if (atomic_read(&conf->r5c_cached_full_stripes) >=

	    min(R5C_FULL_STRIPE_FLUSH_BATCH(conf),

		conf->chunk_sectors >> RAID5_STRIPE_SHIFT(conf)))

		r5l_wake_reclaim(conf->log, 0);

		r5l_wake_reclaim(log, 0);

}



/*
@@ -396,7 +399,7 @@ void r5c_check_cached_full_stripe(struct r5conf *conf) 
 */

static sector_t r5c_log_required_to_flush_cache(struct r5conf *conf)

{

	struct r5l_log *log = conf->log;

	struct r5l_log *log = READ_ONCE(conf->log);



	if (!r5c_is_writeback(log))

		return 0;
@@ -449,7 +452,7 @@ static inline void r5c_update_log_state(struct r5l_log *log) 
void r5c_make_stripe_write_out(struct stripe_head *sh)

{

	struct r5conf *conf = sh->raid_conf;

	struct r5l_log *log = conf->log;

	struct r5l_log *log = READ_ONCE(conf->log);



	BUG_ON(!r5c_is_writeback(log));
@@ -491,7 +494,7 @@ static void r5c_handle_parity_cached(struct stripe_head *sh) 
 */

static void r5c_finish_cache_stripe(struct stripe_head *sh)

{

	struct r5l_log *log = sh->raid_conf->log;

	struct r5l_log *log = READ_ONCE(sh->raid_conf->log);



	if (log->r5c_journal_mode == R5C_JOURNAL_MODE_WRITE_THROUGH) {

		BUG_ON(test_bit(STRIPE_R5C_CACHING, &sh->state));
@@ -692,7 +695,7 @@ static void r5c_disable_writeback_async(struct work_struct *work) 


	/* wait superblock change before suspend */

	wait_event(mddev->sb_wait,

		   conf->log == NULL ||

		   !READ_ONCE(conf->log) ||

		   (!test_bit(MD_SB_CHANGE_PENDING, &mddev->sb_flags) &&

		    (locked = mddev_trylock(mddev))));

	if (locked) {
@@ -1151,7 +1154,7 @@ static void r5l_run_no_space_stripes(struct r5l_log *log) 
static sector_t r5c_calculate_new_cp(struct r5conf *conf)

{

	struct stripe_head *sh;

	struct r5l_log *log = conf->log;

	struct r5l_log *log = READ_ONCE(conf->log);

	sector_t new_cp;

	unsigned long flags;
@@ -1159,12 +1162,12 @@ static sector_t r5c_calculate_new_cp(struct r5conf *conf) 
		return log->next_checkpoint;



	spin_lock_irqsave(&log->stripe_in_journal_lock, flags);

	if (list_empty(&conf->log->stripe_in_journal_list)) {

	if (list_empty(&log->stripe_in_journal_list)) {

		/* all stripes flushed */

		spin_unlock_irqrestore(&log->stripe_in_journal_lock, flags);

		return log->next_checkpoint;

	}

	sh = list_first_entry(&conf->log->stripe_in_journal_list,

	sh = list_first_entry(&log->stripe_in_journal_list,

			      struct stripe_head, r5c);

	new_cp = sh->log_start;

	spin_unlock_irqrestore(&log->stripe_in_journal_lock, flags);
@@ -1399,7 +1402,7 @@ void r5c_flush_cache(struct r5conf *conf, int num) 
	struct stripe_head *sh, *next;



	lockdep_assert_held(&conf->device_lock);

	if (!conf->log)

	if (!READ_ONCE(conf->log))

		return;



	count = 0;
@@ -1420,7 +1423,7 @@ void r5c_flush_cache(struct r5conf *conf, int num) 


static void r5c_do_reclaim(struct r5conf *conf)

{

	struct r5l_log *log = conf->log;

	struct r5l_log *log = READ_ONCE(conf->log);

	struct stripe_head *sh;

	int count = 0;

	unsigned long flags;
@@ -1549,7 +1552,7 @@ static void r5l_reclaim_thread(struct md_thread *thread) 
{

	struct mddev *mddev = thread->mddev;

	struct r5conf *conf = mddev->private;

	struct r5l_log *log = conf->log;

	struct r5l_log *log = READ_ONCE(conf->log);



	if (!log)

		return;
@@ -1591,7 +1594,7 @@ void r5l_quiesce(struct r5l_log *log, int quiesce) 


bool r5l_log_disk_error(struct r5conf *conf)

{

	struct r5l_log *log = conf->log;

	struct r5l_log *log = READ_ONCE(conf->log);



	/* don't allow write if journal disk is missing */

	if (!log)
@@ -2635,7 +2638,7 @@ int r5c_try_caching_write(struct r5conf *conf, 
			  struct stripe_head_state *s,

			  int disks)

{

	struct r5l_log *log = conf->log;

	struct r5l_log *log = READ_ONCE(conf->log);

	int i;

	struct r5dev *dev;

	int to_cache = 0;
@@ -2802,7 +2805,7 @@ void r5c_finish_stripe_write_out(struct r5conf *conf, 
				 struct stripe_head *sh,

				 struct stripe_head_state *s)

{

	struct r5l_log *log = conf->log;

	struct r5l_log *log = READ_ONCE(conf->log);

	int i;

	int do_wakeup = 0;

	sector_t tree_index;
@@ -2941,7 +2944,7 @@ int r5c_cache_data(struct r5l_log *log, struct stripe_head *sh) 
/* check whether this big stripe is in write back cache. */

bool r5c_big_stripe_cached(struct r5conf *conf, sector_t sect)

{

	struct r5l_log *log = conf->log;

	struct r5l_log *log = READ_ONCE(conf->log);

	sector_t tree_index;

	void *slot;
@@ -3049,14 +3052,14 @@ int r5l_start(struct r5l_log *log) 
void r5c_update_on_rdev_error(struct mddev *mddev, struct md_rdev *rdev)

{

	struct r5conf *conf = mddev->private;

	struct r5l_log *log = conf->log;

	struct r5l_log *log = READ_ONCE(conf->log);



	if (!log)

		return;



	if ((raid5_calc_degraded(conf) > 0 ||

	     test_bit(Journal, &rdev->flags)) &&

	    conf->log->r5c_journal_mode == R5C_JOURNAL_MODE_WRITE_BACK)

	    log->r5c_journal_mode == R5C_JOURNAL_MODE_WRITE_BACK)

		schedule_work(&log->disable_writeback_work);

}
@@ -3145,7 +3148,7 @@ int r5l_init_log(struct r5conf *conf, struct md_rdev *rdev) 
	spin_lock_init(&log->stripe_in_journal_lock);

	atomic_set(&log->stripe_in_journal_count, 0);



	conf->log = log;

	WRITE_ONCE(conf->log, log);



	set_bit(MD_HAS_JOURNAL, &conf->mddev->flags);

	return 0;
@@ -3173,7 +3176,7 @@ void r5l_exit_log(struct r5conf *conf) 
	 * 'reconfig_mutex' is held by caller, set 'confg->log' to NULL to

	 * ensure disable_writeback_work wakes up and exits.

	 */

	conf->log = NULL;

	WRITE_ONCE(conf->log, NULL);

	wake_up(&conf->mddev->sb_wait);

	flush_work(&log->disable_writeback_work);